dokku · michaelshobbs · Feb 20, 2016 · Jan 7, 2016 · josegonzalez · Jan 7, 2016
diff --git a/docs/deployment/deployment-tasks.md b/docs/deployment/deployment-tasks.md
@@ -0,0 +1,55 @@
+# Deployment Tasks
+
+Sometimes you need to run a command on at deployment time, but before an app is completely deployed.
+Common use cases include:
+
+* Checking a database is initialised
+* Running database migrations
+* Any commands required to set up the server (e.g. something like a Django `collectstatic`)
+
+## `app.json` and `scripts.dokku`
+
+Dokku accomplishes this by using an `app.json` file. We (mostly) use the same format as Heroku's [app.json](https://devcenter.heroku.com/articles/app-json-schema).
+However, dokku currently only supports the nodes `scripts.dokku.predeploy` and `scripts.dokku.postdeploy`.
+Simply place an `app.json` file in the root of your repository.
+NOTE: `app.json` is only supported in buildpack-deployed apps and postdeploy changes are not committed to the app image.
+
+### Example app.json
+
+```
+{
+  "name": "barebones nodejs",
+  "description": "A barebones Node.js app using Express 4.",
+  "keywords": [
+    "nodejs",
+    "express"
+  ],
+  "repository": "https://github.com/michaelshobbs/node-js-sample",
+  "scripts": {
+    "dokku": {
+      "predeploy": "touch /app/predeploy.test",
+      "postdeploy": "touch /app/postdeploy.test"
+    }
+  },
+  "env": {
+    "SECRET_TOKEN": {
+      "description": "A secret key for verifying the integrity of signed cookies.",
+      "value": "secret"
+    },
+    "WEB_CONCURRENCY": {
+      "description": "The number of processes to run.",
+      "generator": "echo 5"
+    }
+  },
+  "image": "gliderlabs/herokuish",
+  "addons": [
+    "dokku-postgres",
+    "dokku-redis"
+  ],
+  "buildpacks": [
+    {
+      "url": "https://github.com/heroku/heroku-buildpack-nodejs"
+    }
+  ]
+}
+```
diff --git a/docs/development/plugin-triggers.md b/docs/development/plugin-triggers.md
@@ -405,7 +405,7 @@ dokku postgres:link $POSTGRES $APP
 
 - Description: Allows running of commands after a deploy has completed. Dokku core currently uses this to switch traffic on nginx.
 - Invoked by: `dokku deploy`
-- Arguments: `$APP $INTERNAL_PORT $INTERNAL_IP_ADDRESS`
+- Arguments: `$APP $INTERNAL_PORT $INTERNAL_IP_ADDRESS $IMAGE_TAG`
 - Example:
 
 ```shell

diff --git a/dokku b/dokku
@@ -207,7 +207,7 @@ case "$1" in
     done < "$DOKKU_SCALE_FILE"
 
     dokku_log_info1 "Running post-deploy"
-    plugn trigger post-deploy $APP $port $ipaddr
+    plugn trigger post-deploy $APP $port $ipaddr $IMAGE_TAG
 
     # kill the old container
     if [[ -n "$oldids" ]]; then

diff --git a/plugins/00_dokku-standard/exec-app-json-scripts b/plugins/00_dokku-standard/exec-app-json-scripts
@@ -0,0 +1,59 @@
+#!/usr/bin/env bash
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+source "$PLUGIN_CORE_AVAILABLE_PATH/common/functions"
+APP="$1"
+
+case "$0" in
+  *pre-deploy)
+    IMAGE_TAG="$2"
+    IMAGE=$(get_app_image_name $APP $IMAGE_TAG)
+    PHASE_SCRIPT_KEY="predeploy"
+    ;;
+  *post-deploy)
+    IMAGE_TAG="$4"
+    IMAGE=$(get_app_image_name $APP $IMAGE_TAG)
+    PHASE_SCRIPT_KEY="postdeploy"
+    ;;
+esac
+
+get_phase_script() {
+  local PHASE_SCRIPT_KEY="$1"
+  local TMP_WORK_DIR=$(mktemp -d)
+  local APP_JSON_FILE="$TMP_WORK_DIR/app.json"
+  trap 'rm -rf "$TMP_WORK_DIR" > /dev/null' RETURN
+
+  copy_from_image "$IMAGE" "/app/app.json" "$TMP_WORK_DIR" 2>/dev/null || true
+
+  if [[ -f "$APP_JSON_FILE" ]];then
+    local VALUE=$(get_json_value scripts.dokku.${PHASE_SCRIPT_KEY} < "$APP_JSON_FILE")
+  else
+    return 0
+  fi
+
+  echo "$VALUE"
+}
+
+execute_script() {
+  local SCRIPT_CMD=$(get_phase_script "$PHASE_SCRIPT_KEY")
+  if [[ -n "$SCRIPT_CMD" ]];then
+    dokku_log_info1 "Running '$SCRIPT_CMD' in app container"
+    local COMMAND="cd /app ; "
+    local COMMAND+=" for file in /app/.profile.d/*; do source \$file; done ; "
+    local COMMAND+=" echo restoring installation cache... ; "
+    local COMMAND+=" cp -rfp /cache /tmp/ || true ; "
+    local COMMAND+=" $SCRIPT_CMD ; "
+    local COMMAND+=" echo removing installation cache... ; "
+    local COMMAND+=" rm -rf /tmp/cache || true "
+    local DOCKER_ARGS=$(: | plugn trigger docker-args-deploy $APP)
+    local CACHE_DIR="$DOKKU_ROOT/$APP/cache"
+    id=$(docker run $DOKKU_GLOBAL_RUN_ARGS --label=dokku_phase_script=${PHASE_SCRIPT_KEY} -d -v $CACHE_DIR:/cache $DOCKER_ARGS $IMAGE /bin/bash -c "$COMMAND")
+    test "$(docker wait $id)" -eq 0
+    dokku_container_log_verbose_quiet $id
+    if [[ "$PHASE_SCRIPT_KEY" != "postdeploy" ]];then
+      docker commit "$id" "$IMAGE" > /dev/null
+    fi
+  fi
+}
+
+dokku_log_info1 "Attempting to run scripts.dokku.$PHASE_SCRIPT_KEY from app.json (if defined)"
+execute_script
diff --git a/plugins/00_dokku-standard/post-deploy b/plugins/00_dokku-standard/post-deploy
@@ -0,0 +1 @@
+exec-app-json-scripts
diff --git a/plugins/00_dokku-standard/pre-deploy b/plugins/00_dokku-standard/pre-deploy
@@ -0,0 +1 @@
+exec-app-json-scripts
diff --git a/plugins/common/functions b/plugins/common/functions
@@ -599,3 +599,26 @@ get_app_urls() {
     fi
   fi
 }
+
+get_json_value() {
+  # return value of provided json key from a json stream on stdin
+  # JSON_NODE should be expresses as either a top-level object that has no children
+  # or in the format of json.node.path
+  local JSON_NODE="$1"
+  local JSON_NODE=${JSON_NODE//\./\"][\"}
+  local JSON_NODE="[\"${JSON_NODE}\"]"
+  cat | python -c 'import json,sys;obj=json.load(sys.stdin);print json.dumps(obj'"${JSON_NODE}"').strip("\"")';
+}
+
+get_json_keys() {
+  # return space-separated list of json keys from json provided on stdin
+  # JSON_NODE should be expressed as json.node.path and is expected to have children
+  local JSON_NODE="$1"
+  local JSON_NODE=${JSON_NODE//\./\"][\"}
+  local JSON_NODE="[\"${JSON_NODE}\"]"
+  if [[ "$JSON_NODE" == "[\"\"]" ]]; then
+    cat | python -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj.keys())';
+  else
+    cat | python -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj'"${JSON_NODE}"'.keys())';
+  fi
+}
diff --git a/tests/apps/nodejs-express/app.json b/tests/apps/nodejs-express/app.json
@@ -0,0 +1,38 @@
+{
+  "name": "Sample node.js express app",
+  "description": "Used in dokku's test suite",
+  "keywords": [
+    "nodejs",
+    "express",
+    "testing"
+  ],
+  "website": "http://dokku.viewdocs.io/dokku/",
+  "repository": "https://github.com/dokku/dokku",
+  "logo": "https://raw.githubusercontent.com/dokku/dokku/master/docs/assets/dokku.png",
+  "scripts": {
+    "dokku": {
+      "predeploy": "touch /app/predeploy.test",
+      "postdeploy": "touch /app/postdeploy.test"
+    }
+  },
+  "env": {
+    "SECRET_TOKEN": {
+      "description": "A secret key for verifying the integrity of signed cookies.",
+      "value": "secret"
+    },
+    "WEB_CONCURRENCY": {
+      "description": "The number of processes to run.",
+      "generator": "echo 5"
+    }
+  },
+  "image": "gliderlabs/herokuish",
+  "addons": [
+    "dokku-postgres",
+    "dokku-redis"
+  ],
+  "buildpacks": [
+    {
+      "url": "https://github.com/heroku/heroku-buildpack-nodejs"
+    }
+  ]
+}
diff --git a/tests/unit/10_core_1.bats b/tests/unit/10_core_1.bats
@@ -146,3 +146,24 @@ EOF
   echo "status: "$status
   assert_output "3001/udp 3000/tcp 3003"
 }
+
+@test "(core) app.json scripts" {
+  deploy_app
+
+  run /bin/bash -c "dokku run $TEST_APP ls /app/prebuild.test"
+  echo "output: "$output
+  echo "status: "$status
+  assert_failure
+
+  run /bin/bash -c "dokku run $TEST_APP ls /app/predeploy.test"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+
+  CID=$(docker ps -a -q  -f "ancestor=dokku/${TEST_APP}" -f "label=dokku_phase_script=postdeploy")
+  IMAGE_ID=$(docker commit $CID dokku-test/${TEST_APP})
+  run /bin/bash -c "docker run -ti $IMAGE_ID ls /app/postdeploy.test"
+  echo "output: "$output
+  echo "status: "$status
+  assert_success
+}