vaab · November 18, 2022 12:16 · Jan 27, 2015 · Jan 27, 2015
diff --git a/docker-update b/docker-update
@@ -2,8 +2,6 @@
 
 ## Updates an existing image with given script coming from stdin.
 ##
-## $exname build NAME CHARM
-##
 
 exname=$(basename $0)
 
@@ -12,7 +10,6 @@ usage="$exname DOCKER_IMAGE
 Update image with stdin instruction.
 "
 
-
 if [ -z "$1" ]; then
     echo "Error: you should specify a parent image as first argument." >&2
     echo "usage: $usage"
@@ -86,12 +83,20 @@ docker_update() {
     shift
     code=$(cat -)
 
+    ## Saving CMD and ENTRYPOINT
+
     save_cmd=$(docker inspect --format='{{json .Config.Cmd}}' "$image")
     save_entrypoint=$(docker inspect --format='{{json .Config.Entrypoint}}' "$image")
+
+    ## Checking cache in case already built.
+
     if cached=$(echo "$code" | check_cache "$image"); then
 	echo "cached"
         docker tag "$cached" "$image"
     else
+
+        ## Running code in container
+
         container_id=$(docker run -d \
             --entrypoint /bin/bash \
             "$@" "$image" -c \
@@ -106,12 +111,14 @@ docker_update() {
             exit 1
         fi
 
-
         docker commit --author "$exname" --message "$exname" \
             "$container_id" "$image" >/dev/null &&
         docker rm $container_id >/dev/null
         echo "updated"
     fi
+
+    ## Final commit to restore CMD and ENTRYPOINT
+
     docker build -t "$image" - <<EOF >/dev/null 2>&1
 
 FROM $image
@@ -129,8 +136,11 @@ read-0() {
         shift
     done
 }
+
+
 get_image_id() {
     docker inspect --format '{{.Id}}' "$1"
 }
 
+
 docker_update "$image" "$@"
diff --git a/docker-update b/docker-update
@@ -0,0 +1,136 @@
+#!/bin/bash
+
+## Updates an existing image with given script coming from stdin.
+##
+## $exname build NAME CHARM
+##
+
+exname=$(basename $0)
+
+usage="$exname DOCKER_IMAGE
+
+Update image with stdin instruction.
+"
+
+
+if [ -z "$1" ]; then
+    echo "Error: you should specify a parent image as first argument." >&2
+    echo "usage: $usage"
+    exit 1
+fi
+
+image="$1"
+shift
+DOCKER_VERSION=$(docker -v | sed -r 's/^[^0-9.]+([0-9.]+).*$/\1/g')
+
+
+is_cached_code_same() {
+    local cmd
+    cmd="$@"
+    code="$(cat -)"
+    [ "$1" == "-c" ] || return 1
+    [ "$2" == "$code" ] || return 1
+    if echo "$code" | egrep "#\s*docker:\s*ALWAYS\s*" >/dev/null 2>&1; then
+	return 1
+    fi
+    return 0
+}
+
+
+DOCKER_INSPECT_CACHE_FORMAT='{{.Id}}{{"\x00"}}
+{{.Parent}}{{"\x00"}}
+{{if .Config}}{{range $p := .Config.Cmd}}{{$p}}{{"\x00"}}
+{{end}}{{end}}{{"\x00"}}'
+
+DOCKER_INSPECT_CACHE_FORMAT="$(echo "$DOCKER_INSPECT_CACHE_FORMAT" | tr -d "\n")"
+export DOCKER_INSPECT_CACHE_FORMAT
+
+
+##
+# check_cache PARENT_IMAGE
+#
+# Checks if no already stored image has PARENT_IMAGE as parent and
+# same code. If it founds such an image, it'll output its id in stdout
+# and return 0 errlvl. Otherwise it'll return 1 errlvl.
+check_cache() {
+    local image
+    image="$1"
+    shift
+    code="$(cat -)"
+    image_id=$(get_image_id "$image")
+    while read-0 id parent; do
+        cmd=()
+        while true; do
+            read-0 elt
+            if [ "$elt" ]; then
+                cmd=("${cmd[@]}" "$elt")
+            else
+                break
+            fi
+        done
+        if [ "$parent" != "$image_id" ]; then
+            continue
+        fi
+        if echo "$code" | is_cached_code_same "${cmd[@]}"; then
+            ## not used "$id" as there is a spurious \n that is inserted by --format
+            echo $id
+            return 0
+        fi
+    done < <(docker inspect --format "$DOCKER_INSPECT_CACHE_FORMAT" $(docker images -qa))
+    return 1
+}
+
+docker_update() {
+    local image
+    image="$1"
+    shift
+    code=$(cat -)
+
+    save_cmd=$(docker inspect --format='{{json .Config.Cmd}}' "$image")
+    save_entrypoint=$(docker inspect --format='{{json .Config.Entrypoint}}' "$image")
+    if cached=$(echo "$code" | check_cache "$image"); then
+	echo "cached"
+        docker tag "$cached" "$image"
+    else
+        container_id=$(docker run -d \
+            --entrypoint /bin/bash \
+            "$@" "$image" -c \
+            "$code"
+        )
+        if [ "$(docker wait "$container_id")" != "0" ]; then
+            echo "Update of image "$image" failed ! (container: $container_id)"
+            echo "=== code:"
+            echo "$code"
+            echo "=== logs:"
+            docker logs "$container_id"
+            exit 1
+        fi
+
+
+        docker commit --author "$exname" --message "$exname" \
+            "$container_id" "$image" >/dev/null &&
+        docker rm $container_id >/dev/null
+        echo "updated"
+    fi
+    docker build -t "$image" - <<EOF >/dev/null 2>&1
+
+FROM $image
+
+CMD $save_cmd
+ENTRYPOINT $save_entrypoint
+
+EOF
+}
+
+
+read-0() {
+    while [ "$1" ]; do
+        IFS=$'\0' read -r -d '' "$1" || return 1
+        shift
+    done
+}
+get_image_id() {
+    docker inspect --format '{{.Id}}' "$1"
+}
+
+docker_update "$image" "$@"
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