1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
## Output
```text
FROM --platform flag should not use constant value "linux/amd64"
```
## Description
Specifying `--platform` in the Dockerfile `FROM` instruction forces the image to build on only one target platform. This prevents building a multi-platform image from this Dockerfile and you must build on the same platform as specified in `--platform`.
The recommended approach is to:
* Omit `FROM --platform` in the Dockerfile and use the `--platform` argument on the command line.
* Use `$BUILDPLATFORM` or some other combination of variables for the `--platform` argument.
* Stage name should include the platform, OS, or architecture name to indicate that it only contains platform-specific instructions.
## Examples
❌ Bad: using a constant argument for `--platform`
```dockerfile
FROM --platform=linux/amd64 alpine AS base
RUN apk add --no-cache git
```
✅ Good: using the default platform
```dockerfile
FROM alpine AS base
RUN apk add --no-cache git
```
✅ Good: using a meta variable
```dockerfile
FROM --platform=${BUILDPLATFORM} alpine AS base
RUN apk add --no-cache git
```
✅ Good: used in a multi-stage build with a target architecture
```dockerfile
FROM --platform=linux/amd64 alpine AS build_amd64
...
FROM --platform=linux/arm64 alpine AS build_arm64
...
FROM build_${TARGETARCH} AS build
...
```
|
