A Slack Invitator made with Lumen Framework.

Lumen - Slackin

A Slack Invitator made with Lumen Framework and inspired by rauchg/slackin.

That application uses some of my awesome packages:

Badge Poser - Badges generator to Laravel.
Slack API - Laravel easy Slack API.
Language Detector - Automatic set the application language based on user browser preferences.
Lumen Tinker - An interactive shell to Lumen.

Download the source

composer create-project vluzrmos/lumen-slackin

Installation

Copy .env.example to .env and:

Change the APP_KEY to something random string with max 32 characters.

Change the SLACK_TOKEN to the token of your user on slack team, with admin privilegies, you can get it on Slack Web API.

Run

Queue

Start the queue listener:

php artisan queue:listen --timeout=240 1>> /dev/null 2>&1 &

That will start the queue listener in background on *nix computers, to stop that you need to know how to kill a job on your system.

Its hight recomended run the queue on system startup, on linux you should add the following lines to your crontab:

@reboot php /path/to/that/project/artisan queue:listen --timeout=240 1>> /dev/null 2>&1

Scheduled Tasks (Optional)

You may also need to add that command to your cronjob, that will update the users status on every minute:

* * * * *  php /path/to/that/project/artisan schedule:run 1>> /dev/null 2>&1

That will make your queue run in background and ignoring error messages.

Note: If you do not want to use that feature, you just need to set the environment variable SLACK_STATUS_ENABLED to false on your .env file, that will hide the message about users active (online/total) of your team on the homepage:

SLACK_STATUS_ENABLED=false

HTTP Server

Start the http server:

php artisan serve

By default, artisan serve starts on port 8000, if you want to modify it, just starts it by passing --port=NUMBER or just make a VirtualHost on your server (Apache or Nginx) with DocumentRoot on /path/to/that/project/public/ path.

Badge is available

If your need a badge to your slack invitator, just use:

<img src="http://your-domain/badge.svg" />

Example:

Multi-Language Support

By default the system will try to detect if the browser language is available on resources/lang, if available will setup. Available languages:

English - en
French - fr_FR
Portuguese Brazil - pt_BR
German - de_DE

Mobile Devices

That project uses Twitter Bootstrap 3, and it is compatible on small devices.

Using Lumen Slackin

Your team are using this project? Put your link here:

Note: Consider to send a PR to master branch.

License

DBAD.

Hi!

When generating the badge, I get the following error and the Whoops page (on PHP7):

[error] 25675#25675: *516 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught TypeError: Argument 1 passed to Laravel\Lumen\Exceptions\Handler::report() must be an instance of Exception, instance of Error given, called in /var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php on line 369 and defined in /var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Exceptions/Handler.php:24
Stack trace:
#0 /var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php(369): Laravel\Lumen\Exceptions\Handler->report(Object(Error))
#1 /var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php(321): Laravel\Lumen\Application->handleUncaughtException(Object(Error))
#2 [internal function]: Laravel\Lumen\Application->Laravel\Lumen\{closure}(Object(Error))
#3 {main}
  thrown in /var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Exceptions/Handler.php on line 24" while reading response header from upstream, client: 82.226.89.104, server: wallace.scotlandphp.co.uk, request: "GET /badge.svg HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock:", host: "slack.scotlandphp.co.uk"

I used a try/catch(Throwable) and got the following error:

Call to undefined function PUGX\Poser\Calculator\imagettfbbox()

Error {#105
  #message: "Call to undefined function PUGX\Poser\Calculator\imagettfbbox()"
  #code: 0
  #file: "/var/www/lumen-slackin/vendor/badges/poser/src/Calculator/GDTextSizeCalculator.php"
  #line: 33
  -trace: array:37 [
    0 => array:3 [
      "call" => "PUGX\Poser\Calculator\GDTextSizeCalculator->calculateWidth()"
      "file" => "/var/www/lumen-slackin/vendor/badges/poser/src/Render/SvgFlatRender.php:151"
      "args" => array:1 [
        0 => "Scotland PHP"
      ]
    ]
    1 => array:3 [
      "call" => "PUGX\Poser\Render\SvgFlatRender->stringWidth()"
      "file" => "/var/www/lumen-slackin/vendor/badges/poser/src/Render/SvgFlatRender.php:126"
      "args" => array:1 [
        0 => "Scotland PHP"
      ]
    ]
    2 => array:3 [
      "call" => "PUGX\Poser\Render\SvgFlatRender->render()"
      "file" => "/var/www/lumen-slackin/vendor/badges/poser/src/Poser.php:42"
      "args" => array:1 [
        0 => Badge {#120
          -subject: "Scotland PHP"
          -status: "14/148"
          -color: "F1504F"
          -format: "flat"
        }
      ]
    ]
    3 => array:3 [
      "call" => "PUGX\Poser\Poser->generate()"
      "file" => "/var/www/lumen-slackin/vendor/vluzrmos/badge-poser/src/Poser.php:32"
      "args" => array:4 [
        0 => "Scotland PHP"
        1 => "14/148"
        2 => "F1504F"
        3 => "flat"
      ]
    ]
    4 => array:3 [
      "call" => "Vluzrmos\BadgePoser\Poser->generate()"
      "file" => "/var/www/lumen-slackin/app/Services/SlackBadgeService.php:56"
      "args" => array:4 [
        0 => "Scotland PHP"
        1 => "14/148"
        2 => "F1504F"
        3 => "flat"
      ]
    ]
    5 => array:3 [
      "call" => "App\Services\SlackBadgeService->generate()"
      "file" => "/var/www/lumen-slackin/app/Http/Controllers/BadgeController.php:21"
      "args" => array:1 [
        0 => "flat"
      ]
    ]
    6 => array:3 [
      "call" => "App\Http\Controllers\BadgeController->generate()"
      "file" => ""
      "args" => array:2 [
        0 => SlackBadgeService {#129
          #slack: SlackStatusService {#150
            #cache: CacheManager {#139
              #app: Application {#2 …}
              #stores: array:1 [
                "file" => Repository {#149
                  #store: FileStore {#148
                    #files: Filesystem {#24}
                    #directory: "/var/www/lumen-slackin/storage/framework/cache"
                  }
                  #events: Dispatcher {#37
                    #container: Application {#2 …}
                    #listeners: array:1 [
                      "artisan.start" => array:1 [
                        0 => array:1 [
                          0 => Closure {#138
                            class: "Illuminate\Support\ServiceProvider"
                            this: CacheServiceProvider {#133 …}
                            parameters: array:1 [
                              "$artisan" => []
                            ]
                            use: array:1 [
                              "$commands" => array:2 [
                                0 => "command.cache.clear"
                                1 => "command.cache.table"
                              ]
                            ]
                            file: "/var/www/lumen-slackin/vendor/illuminate/support/ServiceProvider.php"
                            line: "176 to 178"
                          }
                        ]
                      ]
                    ]
                    #wildcards: []
                    #sorted: array:1 [
                      "cache.hit" => []
                    ]
                    #firing: []
                    #queueResolver: Closure {#38
                      class: "Illuminate\Events\EventServiceProvider"
                      this: EventServiceProvider {#35 …}
                      use: array:1 [
                        "$app" => Application {#2 …}
                      ]
                      file: "/var/www/lumen-slackin/vendor/illuminate/events/EventServiceProvider.php"
                      line: "17 to 19"
                    }
                  }
                  #default: 60
                }
              ]
              #customCreators: []
            }
            #slack: Team {#130
              #methodsGroup: "team."
              #api: SlackApi {#140
                -client: Client {#141
                  -messageFactory: MessageFactory {#143
                    -errorPlugin: HttpError {#144}
                    -redirectPlugin: Redirect {#145}
                    -customOptions: []
                  }
                  -baseUrl: Url {#142
                    -scheme: ""
                    -host: ""
                    -port: null
                    -username: null
                    -password: null
                    -path: ""
                    -fragment: null
                    -query: null
                  }
                  -defaults: array:5 [
                    "allow_redirects" => true
                    "exceptions" => true
                    "decode_content" => true
                    "verify" => false
                    "headers" => array:1 [
                      "User-Agent" => "Guzzle/5.3.0 PHP/7.0.8-0ubuntu0.16.04.3"
                    ]
                  ]
                  -fsm: RequestFsm {#147
                    -handler: StreamHandler {#146
                      -options: []
                      -lastHeaders: null
                    }
                    -mf: MessageFactory {#143}
                    -maxTransitions: 200
                  }
                  -emitter: null
                }
                -token: "xoxp-12891922214-12892240103-12895015269-53afa303dc"
                -url: "https://slack.com/api"
              }
              #cache: Repository {#149}
              #cachePrefix: "__vlz_slackc_"
            }
            #slackRtm: RealTimeMessage {#131
              #methodsGroup: "rtm."
              #api: SlackApi {#140}
              #cache: Repository {#149}
              #cachePrefix: "__vlz_slackc_"
            }
          }
          #poser: Poser {#124
            -poser: Poser {#151
              -renders: array:3 [
                "flat" => SvgFlatRender {#128
                  -textSizeCalculator: GDTextSizeCalculator {#127
                    +"fontPath": "/var/www/lumen-slackin/vendor/badges/poser/src/Calculator/Font/DejaVuSans.ttf"
                  }
                }
                "svg" => SvgFlatRender {#128}
                "plastic" => SvgRender {#126
                  -textSizeCalculator: GDTextSizeCalculator {#125
                    +"fontPath": "/var/www/lumen-slackin/vendor/badges/poser/src/Calculator/Font/DejaVuSans.ttf"
                  }
                }
              ]
            }
          }
          #allowedBadgeFormats: array:2 [
            0 => "flat"
            1 => "plastic"
          ]
        }
        1 => Request {#79
          #json: null
          #userResolver: Closure {#80
            class: "Laravel\Lumen\Application"
            this: Application {#2 …}
            file: "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php"
            line: "678 to 680"
          }
          #routeResolver: Closure {#63
            class: "Laravel\Lumen\Application"
            this: Application {#2 …}
            file: "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php"
            line: "680 to 682"
          }
          +attributes: ParameterBag {#81
            #parameters: []
          }
          +request: ParameterBag {#87
            #parameters: []
          }
          +query: ParameterBag {#87}
          +server: ServerBag {#84
            #parameters: array:51 [
              "USER" => "www-data"
              "HOME" => "/var/www"
              "HTTP_COOKIE" => "__cfduid=d56525bd67b791a5cc461164e0e212f441465497044; SS_MID=84309801-5c93-474f-87c6-ef8e73a64517ipaw7zgi"
              "HTTP_ACCEPT_LANGUAGE" => "en-GB,en;q=0.8,fr;q=0.6"
              "HTTP_ACCEPT_ENCODING" => "gzip, deflate, sdch, br"
              "HTTP_DNT" => "1"
              "HTTP_ACCEPT" => "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8"
              "HTTP_USER_AGENT" => "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36"
              "HTTP_UPGRADE_INSECURE_REQUESTS" => "1"
              "HTTP_CACHE_CONTROL" => "max-age=0"
              "HTTP_CONNECTION" => "keep-alive"
              "HTTP_HOST" => "slack.scotlandphp.co.uk"
              "REDIRECT_STATUS" => "200"
              "SERVER_NAME" => "wallace.scotlandphp.co.uk"
              "SERVER_PORT" => "443"
              "SERVER_ADDR" => "149.202.175.239"
              "REMOTE_PORT" => "53371"
              "REMOTE_ADDR" => "82.226.89.104"
              "SERVER_SOFTWARE" => "nginx/1.10.0"
              "GATEWAY_INTERFACE" => "CGI/1.1"
              "HTTPS" => "on"
              "REQUEST_SCHEME" => "https"
              "SERVER_PROTOCOL" => "HTTP/1.1"
              "DOCUMENT_ROOT" => "/var/www/lumen-slackin/public"
              "DOCUMENT_URI" => "/index.php"
              "REQUEST_URI" => "/badge.svg"
              "SCRIPT_NAME" => "/index.php"
              "CONTENT_LENGTH" => ""
              "CONTENT_TYPE" => ""
              "REQUEST_METHOD" => "GET"
              "QUERY_STRING" => ""
              "SCRIPT_FILENAME" => "/var/www/lumen-slackin/public/index.php"
              "PATH_INFO" => ""
              "FCGI_ROLE" => "RESPONDER"
              "PHP_SELF" => "/index.php"
              "REQUEST_TIME_FLOAT" => 1476946505.2324
              "REQUEST_TIME" => 1476946505
              "APP_ENV" => "production"
              "APP_DEBUG" => "false"
              "APP_KEY" => "Sc46SNNd9HtvCpQhf8VfEjhm6sBryjnu"
              "APP_LOCALE" => "en"
              "APP_FALLBACK_LOCALE" => "en"
              "CACHE_DRIVER" => "file"
              "SESSION_DRIVER" => "file"
              "QUEUE_DRIVER" => "sync"
              "SLACK_TOKEN" => "xoxp-12891922214-12892240103-12895015269-53afa303dc"
              "SLACK_STATUS_ENABLED" => "true"
              "LANG_DETECTOR_AUTODETECT" => "true"
              "LANG_DETECTOR_DRIVER" => "browser"
              "LANG_DETECTOR_SEGMENT" => ""
              "LANG_DETECTOR_LANGUAGES" => "en,pt_BR,de_DE"
            ]
          }
          +files: FileBag {#83
            #parameters: []
          }
          +cookies: ParameterBag {#82
            #parameters: array:2 [
              "__cfduid" => null
              "SS_MID" => null
            ]
          }
          +headers: HeaderBag {#85
            #headers: array:12 [
              "cookie" => array:1 [
                0 => "__cfduid=d56525bd67b791a5cc461164e0e212f441465497044; SS_MID=84309801-5c93-474f-87c6-ef8e73a64517ipaw7zgi"
              ]
              "accept-language" => array:1 [
                0 => "en-GB,en;q=0.8,fr;q=0.6"
              ]
              "accept-encoding" => array:1 [
                0 => "gzip, deflate, sdch, br"
              ]
              "dnt" => array:1 [
                0 => "1"
              ]
              "accept" => array:1 [
                0 => "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8"
              ]
              "user-agent" => array:1 [
                0 => "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36"
              ]
              "upgrade-insecure-requests" => array:1 [
                0 => "1"
              ]
              "cache-control" => array:1 [
                0 => "max-age=0"
              ]
              "connection" => array:1 [
                0 => "keep-alive"
              ]
              "host" => array:1 [
                0 => "slack.scotlandphp.co.uk"
              ]
              "content-length" => array:1 [
                0 => ""
              ]
              "content-type" => array:1 [
                0 => ""
              ]
            ]
            #cacheControl: array:1 [
              "max-age" => "0"
            ]
          }
          #content: null
          #languages: array:3 [
            0 => "en_GB"
            1 => "en"
            2 => "fr"
          ]
          #charsets: null
          #encodings: null
          #acceptableContentTypes: null
          #pathInfo: null
          #requestUri: null
          #baseUrl: null
          #basePath: null
          #method: "GET"
          #format: null
          #session: Store {#88
            #id: "0e554e36ef299a84db7399b643bcbf5770a9507e"
            #name: "laravel_session"
            #attributes: array:1 [
              "_token" => "PoaDrcZbTOIVIWXuPFI5AuZp9GqnpaNFWBcuhoL1"
            ]
            #bags: []
            #metaBag: MetadataBag {#89
              -name: "__metadata"
              -storageKey: "_sf2_meta"
              #meta: &12 array:3 [
                "u" => 1476946505
                "c" => 1476946505
                "l" => "0"
              ]
              -lastUsed: 1476946505
              -updateThreshold: 0
            }
            #bagData: array:1 [
              "_sf2_meta" => &12 array:3 [&12]
            ]
            #handler: FileSessionHandler {#91
              #files: Filesystem {#24}
              #path: "/var/www/lumen-slackin/storage/framework/sessions"
            }
            #started: true
          }
          #locale: null
          #defaultLocale: "en"
        }
      ]
    ]
    7 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/container/Container.php:502"
      "args" => array:2 [
        0 => array:2 [
          0 => BadgeController {#99
            #middleware: []
          }
          1 => "generate"
        ]
        1 => array:2 [
          0 => SlackBadgeService {#129}
          1 => Request {#79}
        ]
      ]
    ]
    8 => array:3 [
      "call" => "Illuminate\Container\Container->call()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1348"
      "args" => array:2 [
        0 => array:2 [
          0 => BadgeController {#99}
          1 => "generate"
        ]
        1 => []
      ]
    ]
    9 => array:3 [
      "call" => "Laravel\Lumen\Application->callControllerCallable()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1312"
      "args" => array:2 [
        0 => array:2 [
          0 => BadgeController {#99}
          1 => "generate"
        ]
        1 => []
      ]
    ]
    10 => array:3 [
      "call" => "Laravel\Lumen\Application->callLumenController()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1284"
      "args" => array:3 [
        0 => BadgeController {#99}
        1 => "generate"
        2 => array:3 [
          0 => true
          1 => array:1 [
            "uses" => "App\Http\Controllers\BadgeController@generate"
          ]
          2 => []
        ]
      ]
    ]
    11 => array:3 [
      "call" => "Laravel\Lumen\Application->callControllerAction()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1252"
      "args" => array:1 [
        0 => array:3 [
          0 => true
          1 => array:1 [
            "uses" => "App\Http\Controllers\BadgeController@generate"
          ]
          2 => []
        ]
      ]
    ]
    12 => array:3 [
      "call" => "Laravel\Lumen\Application->callActionOnArrayBasedRoute()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1237"
      "args" => array:1 [
        0 => array:3 [
          0 => true
          1 => array:1 [
            "uses" => "App\Http\Controllers\BadgeController@generate"
          ]
          2 => []
        ]
      ]
    ]
    13 => array:3 [
      "call" => "Laravel\Lumen\Application->handleFoundRoute()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1158"
      "args" => array:1 [
        0 => array:3 [
          0 => true
          1 => array:1 [
            "uses" => "App\Http\Controllers\BadgeController@generate"
          ]
          2 => []
        ]
      ]
    ]
    14 => array:3 [
      "call" => "Laravel\Lumen\Application->Laravel\Lumen\{closure}()"
      "file" => ""
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    15 => array:3 [
      "call" => "call_user_func()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:139"
      "args" => array:2 [
        0 => Closure {#75
          class: "Laravel\Lumen\Application"
          this: Application {#2 …}
          use: array:2 [
            "$method" => "GET"
            "$pathInfo" => "/badge.svg"
          ]
          file: "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php"
          line: "1156 to 1164"
        }
        1 => Request {#79}
      ]
    ]
    16 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Http/Middleware/VerifyCsrfToken.php:42"
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    17 => array:3 [
      "call" => "Laravel\Lumen\Http\Middleware\VerifyCsrfToken->handle()"
      "file" => ""
      "args" => array:2 [
        0 => Request {#79}
        1 => Closure {#66
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:1 [
            "$destination" => Closure {#75}
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "138 to 140"
        }
      ]
    ]
    18 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:124"
      "args" => array:2 [
        0 => array:2 [
          0 => VerifyCsrfToken {#119
            #encrypter: Encrypter {#94
              #cipher: "AES-256-CBC"
              #key: "Sc46SNNd9HtvCpQhf8VfEjhm6sBryjnu"
            }
          }
          1 => "handle"
        ]
        1 => array:2 [
          0 => Request {#79}
          1 => Closure {#66}
        ]
      ]
    ]
    19 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/view/Middleware/ShareErrorsFromSession.php:54"
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    20 => array:3 [
      "call" => "Illuminate\View\Middleware\ShareErrorsFromSession->handle()"
      "file" => ""
      "args" => array:2 [
        0 => Request {#79}
        1 => Closure {#77
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:2 [
            "$stack" => Closure {#66}
            "$pipe" => "Laravel\Lumen\Http\Middleware\VerifyCsrfToken"
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "114 to 126"
        }
      ]
    ]
    21 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:124"
      "args" => array:2 [
        0 => array:2 [
          0 => ShareErrorsFromSession {#107
            #view: Factory {#118
              #engines: EngineResolver {#113
                #resolvers: array:2 [
                  "php" => Closure {#114
                    class: "Illuminate\View\ViewServiceProvider"
                    this: ViewServiceProvider {#109 …}
                    file: "/var/www/lumen-slackin/vendor/illuminate/view/ViewServiceProvider.php"
                    line: "56 to 56"
                  }
                  "blade" => Closure {#116
                    class: "Illuminate\View\ViewServiceProvider"
                    this: ViewServiceProvider {#109 …}
                    use: array:1 [
                      "$app" => Application {#2 …}
                    ]
                    file: "/var/www/lumen-slackin/vendor/illuminate/view/ViewServiceProvider.php"
                    line: "78 to 80"
                  }
                ]
                #resolved: []
              }
              #finder: FileViewFinder {#117
                #files: Filesystem {#24}
                #paths: array:1 [
                  0 => "/var/www/lumen-slackin/resources/views"
                ]
                #views: []
                #hints: []
                #extensions: array:2 [
                  0 => "blade.php"
                  1 => "php"
                ]
              }
              #events: Dispatcher {#37}
              #container: Application {#2 …}
              #shared: array:3 [
                "__env" => Factory {#118}
                "app" => Application {#2 …}
                "errors" => ViewErrorBag {#106
                  #bags: []
                }
              ]
              #aliases: []
              #names: []
              #extensions: array:2 [
                "blade.php" => "blade"
                "php" => "php"
              ]
              #composers: []
              #sections: []
              #sectionStack: []
              #renderCount: 0
            }
          }
          1 => "handle"
        ]
        1 => array:2 [
          0 => Request {#79}
          1 => Closure {#77}
        ]
      ]
    ]
    22 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/session/Middleware/StartSession.php:62"
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    23 => array:3 [
      "call" => "Illuminate\Session\Middleware\StartSession->handle()"
      "file" => ""
      "args" => array:2 [
        0 => Request {#79}
        1 => Closure {#73
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:2 [
            "$stack" => Closure {#77}
            "$pipe" => "Illuminate\View\Middleware\ShareErrorsFromSession"
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "114 to 126"
        }
      ]
    ]
    24 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:124"
      "args" => array:2 [
        0 => array:2 [
          0 => StartSession {#95
            #manager: SessionManager {#104
              #app: Application {#2 …}
              #customCreators: []
              #drivers: array:1 [
                "file" => Store {#88}
              ]
            }
            #sessionHandled: true
          }
          1 => "handle"
        ]
        1 => array:2 [
          0 => Request {#79}
          1 => Closure {#73}
        ]
      ]
    ]
    25 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/cookie/Middleware/AddQueuedCookiesToResponse.php:37"
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    26 => array:3 [
      "call" => "Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse->handle()"
      "file" => ""
      "args" => array:2 [
        0 => Request {#79}
        1 => Closure {#72
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:2 [
            "$stack" => Closure {#73}
            "$pipe" => "Illuminate\Session\Middleware\StartSession"
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "114 to 126"
        }
      ]
    ]
    27 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:124"
      "args" => array:2 [
        0 => array:2 [
          0 => AddQueuedCookiesToResponse {#71
            #cookies: CookieJar {#98
              #path: "/"
              #domain: null
              #queued: []
            }
          }
          1 => "handle"
        ]
        1 => array:2 [
          0 => Request {#79}
          1 => Closure {#72}
        ]
      ]
    ]
    28 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/cookie/Middleware/EncryptCookies.php:59"
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    29 => array:3 [
      "call" => "Illuminate\Cookie\Middleware\EncryptCookies->handle()"
      "file" => ""
      "args" => array:2 [
        0 => Request {#79}
        1 => Closure {#74
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:2 [
            "$stack" => Closure {#72}
            "$pipe" => "Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse"
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "114 to 126"
        }
      ]
    ]
    30 => array:3 [
      "call" => "call_user_func_array()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:124"
      "args" => array:2 [
        0 => array:2 [
          0 => EncryptCookies {#90
            #encrypter: Encrypter {#94}
            #except: []
          }
          1 => "handle"
        ]
        1 => array:2 [
          0 => Request {#79}
          1 => Closure {#74}
        ]
      ]
    ]
    31 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->Illuminate\Pipeline\{closure}()"
      "file" => ""
      "args" => array:1 [
        0 => Request {#79}
      ]
    ]
    32 => array:3 [
      "call" => "call_user_func()"
      "file" => "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php:102"
      "args" => array:2 [
        0 => Closure {#86
          class: "Illuminate\Pipeline\Pipeline"
          this: Pipeline {#78 …}
          parameters: array:1 [
            "$passable" => []
          ]
          use: array:2 [
            "$stack" => Closure {#74}
            "$pipe" => "Illuminate\Cookie\Middleware\EncryptCookies"
          ]
          file: "/var/www/lumen-slackin/vendor/illuminate/pipeline/Pipeline.php"
          line: "114 to 126"
        }
        1 => Request {#79}
      ]
    ]
    33 => array:3 [
      "call" => "Illuminate\Pipeline\Pipeline->then()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1387"
      "args" => array:1 [
        0 => Closure {#75}
      ]
    ]
    34 => array:3 [
      "call" => "Laravel\Lumen\Application->sendThroughPipeline()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1164"
      "args" => array:2 [
        0 => array:5 [
          0 => "Illuminate\Cookie\Middleware\EncryptCookies"
          1 => "Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse"
          2 => "Illuminate\Session\Middleware\StartSession"
          3 => "Illuminate\View\Middleware\ShareErrorsFromSession"
          4 => "Laravel\Lumen\Http\Middleware\VerifyCsrfToken"
        ]
        1 => Closure {#75}
      ]
    ]
    35 => array:3 [
      "call" => "Laravel\Lumen\Application->dispatch()"
      "file" => "/var/www/lumen-slackin/vendor/laravel/lumen-framework/src/Application.php:1104"
      "args" => array:1 [
        0 => null
      ]
    ]
    36 => array:3 [
      "call" => "Laravel\Lumen\Application->run()"
      "file" => "/var/www/lumen-slackin/public/index.php:28"
      "args" => []
    ]
  ]
}

Turns out gd was missing from my server. The dependency on gd is not made explicit in the composer.json file.