Deprecate auto detection of container user (#7930)

There is no reliable way to handle fallbacks for
MinIO deployments, due to various command line
options and multiple locations which require
access inside container.

Parsing command line options is tricky to figure
out which is the backend disk etc, we did try
to fix this in implementations of check-user.go
but it wasn't complete and introduced more bugs.

This PR simplifies the entire approach to rather
than running Docker container as non-root by default
always, it allows users to opt-in. Such that they
are aware that that is what they are planning to do.

In-fact there are other ways docker containers can
be run as regular users, without modifying our
internal behavior and adding more complexities.

.gitignore

@@ -22,5 +22,4 @@ prime/
 stage/
 .sia_temp/
 config.json
-dockerscripts/check-user
 dockerscripts/healthcheck

Dockerfile

@@ -10,8 +10,7 @@ RUN  \
      apk add --no-cache git && \
      git clone https://github.com/minio/minio && cd minio && \
      go install -v -ldflags "$(go run buildscripts/gen-ldflags.go)" && \
-     cd dockerscripts; go build -tags kqueue -ldflags "-s -w" -o /usr/bin/healthcheck healthcheck.go && \
+     cd dockerscripts; go build -tags kqueue -ldflags "-s -w" -o /usr/bin/healthcheck healthcheck.go
-     go build -tags kqueue -ldflags "-s -w" -o /usr/bin/check-user check-user.go
 
 FROM alpine:3.9
 
@@ -23,7 +22,6 @@ EXPOSE 9000
 
 COPY --from=0 /go/bin/minio /usr/bin/minio
 COPY --from=0 /usr/bin/healthcheck /usr/bin/healthcheck
-COPY --from=0 /usr/bin/check-user /usr/bin/check-user
 COPY dockerscripts/docker-entrypoint.sh /usr/bin/
 
 RUN  \

Dockerfile.dev

@@ -2,7 +2,7 @@ FROM alpine:3.9
 
 LABEL maintainer="MinIO Inc <dev@min.io>"
 
-COPY dockerscripts/docker-entrypoint.sh dockerscripts/healthcheck dockerscripts/check-user /usr/bin/
+COPY dockerscripts/docker-entrypoint.sh dockerscripts/healthcheck /usr/bin/
 COPY minio /usr/bin/
 
 ENV MINIO_UPDATE off
@@ -14,8 +14,7 @@ RUN \
      echo 'hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4' >> /etc/nsswitch.conf && \
      chmod +x /usr/bin/minio  && \
      chmod +x /usr/bin/docker-entrypoint.sh && \
-     chmod +x /usr/bin/healthcheck && \
+     chmod +x /usr/bin/healthcheck
-     chmod +x /usr/bin/check-user
 
 EXPOSE 9000
 

Dockerfile.release

@@ -7,15 +7,13 @@ ENV GO111MODULE on
 RUN  \
      apk add --no-cache git && \
      git clone https://github.com/minio/minio && cd minio/dockerscripts && \
-     go build -tags kqueue -ldflags "-s -w" -o /usr/bin/healthcheck healthcheck.go && \
+     go build -tags kqueue -ldflags "-s -w" -o /usr/bin/healthcheck healthcheck.go
-     go build -tags kqueue -ldflags "-s -w" -o /usr/bin/check-user check-user.go
 
 FROM alpine:3.9
 
 LABEL maintainer="MinIO Inc <dev@min.io>"
 
 COPY --from=0 /usr/bin/healthcheck /usr/bin/healthcheck
-COPY --from=0 /usr/bin/check-user /usr/bin/check-user
 COPY dockerscripts/docker-entrypoint.sh /usr/bin/
 
 ENV MINIO_UPDATE off
@@ -28,8 +26,7 @@ RUN \
      curl https://dl.min.io/server/minio/release/linux-amd64/minio > /usr/bin/minio && \
      chmod +x /usr/bin/minio  && \
      chmod +x /usr/bin/docker-entrypoint.sh && \
-     chmod +x /usr/bin/healthcheck && \
+     chmod +x /usr/bin/healthcheck
-     chmod +x /usr/bin/check-user
 
 EXPOSE 9000
 

Makefile

@@ -73,7 +73,6 @@ build: checks
 	@echo "Building minio binary to './minio'"
 	@GO111MODULE=on GOFLAGS="" CGO_ENABLED=0 go build -tags kqueue --ldflags $(BUILD_LDFLAGS) -o $(PWD)/minio 1>/dev/null
 	@GO111MODULE=on GOFLAGS="" CGO_ENABLED=0 go build -tags kqueue --ldflags $(BUILD_LDFLAGS) -o $(PWD)/dockerscripts/healthcheck $(PWD)/dockerscripts/healthcheck.go 1>/dev/null
-	@GO111MODULE=on GOFLAGS="" CGO_ENABLED=0 go build -tags kqueue --ldflags $(BUILD_LDFLAGS) -o $(PWD)/dockerscripts/check-user $(PWD)/dockerscripts/check-user.go 1>/dev/null
 
 docker: build
 	@docker build -t $(TAG) . -f Dockerfile.dev

dockerscripts/check-user.go

@@ -1,135 +0,0 @@
-// +build ignore
-
-/*
- * MinIO Cloud Storage, (C) 2019 MinIO, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-	"os/user"
-	"syscall"
-
-	"github.com/minio/cli"
-	minio "github.com/minio/minio/cmd"
-)
-
-var defaultUserGroup string
-
-func init() {
-	username := os.Getenv("MINIO_USERNAME")
-	groupname := os.Getenv("MINIO_GROUPNAME")
-	defaultUserGroup = username + ":" + groupname
-}
-
-func getUserGroup(path string) (string, error) {
-	fi, err := os.Stat(minio.PathJoin(path, ".minio.sys"))
-	if err != nil {
-		// Fresh directory we should default to what was requested by user.
-		if os.IsNotExist(err) {
-			fi, err = os.Stat(path)
-			if err != nil {
-				return "", err
-			}
-		} else {
-			return "", err
-		}
-	}
-	stat, ok := fi.Sys().(*syscall.Stat_t)
-	if !ok {
-		// Unable to figure out uid/gid, default to defaultUserGroup
-		return defaultUserGroup, nil
-	}
-	u, err := user.LookupId(fmt.Sprintf("%d", stat.Uid))
-	if err != nil {
-		return fmt.Sprintf("%d:%d", stat.Uid, stat.Gid), nil
-	}
-	g, err := user.LookupGroupId(fmt.Sprintf("%d", stat.Gid))
-	if err != nil {
-		return fmt.Sprintf("%d:%d", stat.Uid, stat.Gid), nil
-	}
-	return fmt.Sprintf("%s:%s", u.Username, g.Name), nil
-}
-
-func main() {
-	app := cli.NewApp()
-	app.Flags = append(minio.ServerFlags, minio.GlobalFlags...)
-	app.Action = func(ctx *cli.Context) {
-		// Fetch address option
-		serverAddr := ctx.GlobalString("address")
-		if serverAddr == "" || serverAddr == ":9000" {
-			serverAddr = ctx.String("address")
-		}
-		if ctx.Args().First() == "help" {
-			cli.ShowCommandHelpAndExit(ctx, "check-user", 1)
-		}
-		if ctx.Args().First() != "minio" {
-			cli.ShowCommandHelpAndExit(ctx, "check-user", 1)
-		}
-		args := cli.Args(ctx.Args().Tail())
-		if !args.Present() {
-			cli.ShowCommandHelpAndExit(ctx, "check-user", 1)
-		}
-		var ug string
-		var err error
-		switch args.First() {
-		case "gateway":
-			args = cli.Args(args.Tail())
-			if args.First() != "nas" {
-				fmt.Println(defaultUserGroup)
-				return
-			}
-			args = cli.Args(args.Tail())
-			if args.First() == "" {
-				fmt.Println("")
-				return
-			}
-			ug, err = getUserGroup(args.First())
-			if err != nil {
-				log.Fatalln(err)
-			}
-		case "server":
-			var setArgs [][]string
-			setArgs, err = minio.GetAllSets(args.Tail()...)
-			if err != nil {
-				log.Fatalln(err)
-			}
-			var endpoints minio.EndpointList
-			_, endpoints, _, err = minio.CreateEndpoints(serverAddr, setArgs...)
-			if err != nil {
-				log.Fatalln(err)
-			}
-			for _, endpoint := range endpoints {
-				if !endpoint.IsLocal {
-					continue
-				}
-				ug, err = getUserGroup(endpoint.Path)
-				if err != nil {
-					log.Fatalln(err)
-				}
-				break
-			}
-		default:
-			cli.ShowCommandHelpAndExit(ctx, "check-user", 1)
-		}
-		fmt.Println(ug)
-	}
-	if err := app.Run(os.Args); err != nil {
-		log.Fatalln(err)
-	}
-}

dockerscripts/docker-entrypoint.sh

@@ -15,9 +15,6 @@
 # limitations under the License.
 #
 
-export MINIO_USERNAME=${MINIO_USERNAME:-"minio"}
-export MINIO_GROUPNAME=${MINIO_GROUPNAME:-"minio"}
-
 # If command starts with an option, prepend minio.
 if [ "${1}" != "minio" ]; then
     if [ -n "${1}" ]; then
@@ -42,37 +39,21 @@ docker_secrets_env() {
     fi
 }
 
-## Create UID/GID based on available environment variables.
+# su-exec to requested user, if service cannot run exec will fail.
-docker_set_uid_gid() {
+docker_switch_user() {
+    if [ -z "${MINIO_USERNAME}" ] || [ -z "${MINIO_GROUPNAME}" ]; then
         addgroup -S "$MINIO_GROUPNAME" >/dev/null 2>&1 && \
             adduser -S -G "$MINIO_GROUPNAME" "$MINIO_USERNAME" >/dev/null 2>&1
-}
 
-# su-exec to requested user, if user cannot be requested
+        exec su-exec "${MINIO_USERNAME}:${MINIO_GROUPNAME}" "$@"
-# existing user is used automatically.
+    else
-docker_switch_user() {
-    owner=$(check-user "$@")
-    if [ "${owner}" != "${MINIO_USERNAME}:${MINIO_GROUPNAME}" ]; then
-        ## Print the message only if we are not using non-default username:groupname.
-        if [ "${MINIO_USERNAME}:${MINIO_GROUPNAME}" != "minio:minio" ]; then
-            echo "Requested username/group ${MINIO_USERNAME}:${MINIO_GROUPNAME} cannot be used"
-            echo "Found existing data with user ${owner}, we will continue and use ${owner} instead."
-            return
-        fi
-    fi
-    # check if su-exec is allowed, if yes proceed proceed.
-    if su-exec "${owner}" "/bin/ls" >/dev/null 2>&1; then
-        exec su-exec "${owner}" "$@"
-    fi
         # fallback
         exec "$@"
+    fi
 }
 
 ## Set access env from secrets if necessary.
 docker_secrets_env
 
-## User Input UID and GID
-docker_set_uid_gid
-
 ## Switch to user if applicable.
 docker_switch_user "$@"

docs/docker/README.md

@@ -58,20 +58,19 @@ docker run -p 9000:9000 --name minio1 \
   minio/minio server /data
 ```
 
-### Run MinIO Docker as non root user
+### Run MinIO Docker as regular user
-MinIO server runs as non-root within the container by default. However, this is applicable only if you're deploying new MinIO instance (not upgrading from older releases). Deployments upgrading from older MinIO deployments, will continue to run as the user previously used if any.
+MinIO server doesn't run as a regular user by default in docker containers. To run MinIO container as regular user use environment variables `MINIO_USERNAME` and `MINIO_GROUPNAME`.
 
-By default `minio` is username and groupname. Use environment variables `MINIO_USERNAME` and `MINIO_GROUPNAME` to override these default values.
+> NOTE: If you are upgrading from existing deployments, you need to make sure this user has write access to previous persistent volumes. MinIO will not migrate the content automatically.
 
 #### GNU/Linux and macOS
 ```sh
 docker run -p 9000:9000 --name minio1 \
   -e "MINIO_ACCESS_KEY=AKIAIOSFODNN7EXAMPLE" \
   -e "MINIO_SECRET_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY" \
-  -e "MINIO_USERNAME=custom" \
+  -e "MINIO_USERNAME=minio-user" \
-  -e "MINIO_GROUPNAME=custom" \
+  -e "MINIO_GROUPNAME=minio-user" \
   -v /mnt/data:/data \
-  -v /mnt/config:/root/.minio \
   minio/minio server /data
 ```
 
@@ -80,10 +79,9 @@ docker run -p 9000:9000 --name minio1 \
 docker run -p 9000:9000 --name minio1 \
   -e "MINIO_ACCESS_KEY=AKIAIOSFODNN7EXAMPLE" \
   -e "MINIO_SECRET_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY" \
-  -e "MINIO_USERNAME=custom" \
+  -e "MINIO_USERNAME=minio-user" \
-  -e "MINIO_GROUPNAME=custom" \
+  -e "MINIO_GROUPNAME=minio-user" \
   -v D:\data:/data \
-  -v D:\minio\config:/root/.minio \
   minio/minio server /data
 ```