write in shared volumes docker

前端未结

关注

 2  1747

I have a docker with a php application on it

I have a share volume, for example

/home/me/dev/site <=> /var/www/site

I can wri

相关标签:

2条回答

忘了有多久

2020-11-28 03:22
(Bind-mounted) volumes in Docker will maintain the permissions that are set on the Docker host itself. You can use this to set the permissions on those files and directories before using them in the container.

Some background;

Permissions in Linux are based on user and group ids ('uid' / 'gid'). Even though you see a user- and group name as owner, those names aren't actually important in Linux, they are only there to make it easier for you to see who's the owner of a file (they are looked up from the /etc/passwd file).

You can set any uid/gid on a file; a user doesn't have to exist when setting those permissions. For example;
```
touch foobar && sudo chown 1234:5678 foobar && ls -la foobar

# UID and GID are set to 1234 / 5678, even though there's no such user
-rw-rw-r-- 1 1234 5678 0 Mar 25 19:14 foobar
```
Checking permissions (inside and outside a container)

As mentioned above, Docker maintains ownership of the host when using a volume. This example shows that permissions and ownership in the volume are the same outside and inside a container;
```
# (First create a dummy site)

mkdir -p volume-example/site && cd volume-example
echo "<html><body>hello world</body></html>" > site/index.html

# Permissions on the Docker host;

ls -n site

# total 4
# -rw-rw-r-- 1 1002 1002 38 Mar 25 19:15 index.html

# And, permissions inside a nginx container, using it as volume;

sudo docker run --rm -v $(pwd)/site:/var/www nginx ls -n /var/www

# total 4
# -rw-rw-r-- 1 1002 1002 38 Mar 25 19:15 index.html
```
Setting the permissions

As explained, a user doesn't have to exist in order to use them, so even if we don't have a www-data user on the Docker host, we can still set the correct permissions if we know the "uid" and "gid" of that user inside the container;

Let's see what the uid and gid of the www-data user is inside the container;
```
sudo docker run --rm nginx id www-data

# uid=33(www-data) gid=33(www-data) groups=33(www-data)
```
First check the state before changing the permissions. This time we run the nginx container as user www-data;
```
sudo docker run \
  --rm \
  --volume $(pwd)/site:/var/www \
  --user www-data nginx touch /var/www/can-i-write.txt

# touch: cannot touch `/var/www/can-i-write.txt': Permission denied
```
Next, set the permissions on the local directory, and see if we are able to write;
```
sudo chown -R 33:33 site

sudo docker run \
   --rm \
   --volume $(pwd)/site:/var/www \
   --user www-data nginx touch /var/www/can-i-write.txt
```
Success!
0 讨论(0)
发布评论:

提交评论
- 加载中...
独厮守ぢ

2020-11-28 03:23
Add the following lines to your dockerfile and rebuild your image
```
RUN usermod -u 1000 www-data
RUN usermod -G staff www-data
```
0 讨论(0)
发布评论:

提交评论
- 加载中...

write in shared volumes docker

Checking permissions (inside and outside a container)

Setting the permissions