testcontainers
[Bug]: Copy a file WithResourceMapping leads to an (empty) directory in the container
Testcontainers version
4.6.0
Using the latest Testcontainers version?
Yes
Host OS
Mac
Host arch
ARM
.NET version
9.0.302
Docker version
➜ podman version
Client: Podman Engine
Version: 5.5.2
API Version: 5.5.2
Go Version: go1.24.4
Built: Tue Jun 24 16:41:45 2025
Build Origin: brew
OS/Arch: darwin/arm64
Server: Podman Engine
Version: 5.2.3
API Version: 5.2.3
Go Version: go1.22.7
Built: Tue Sep 24 02:00:00 2024
OS/Arch: linux/arm64
Docker info
➜ podman info
Client:
APIVersion: 5.5.2
BuildOrigin: brew
Built: 1750776105
BuiltTime: Tue Jun 24 16:41:45 2025
GitCommit: ""
GoVersion: go1.24.4
Os: darwin
OsArch: darwin/arm64
Version: 5.5.2
host:
arch: arm64
buildahVersion: 1.37.3
cgroupControllers:
- cpuset
- cpu
- io
- memory
- pids
- rdma
- misc
cgroupManager: systemd
cgroupVersion: v2
conmon:
package: conmon-2.1.12-2.fc40.aarch64
path: /usr/bin/conmon
version: 'conmon version 2.1.12, commit: '
cpuUtilization:
idlePercent: 98.24
systemPercent: 0.73
userPercent: 1.03
cpus: 6
databaseBackend: sqlite
distribution:
distribution: fedora
variant: coreos
version: "40"
eventLogger: journald
freeLocks: 2031
hostname: localhost.localdomain
idMappings:
gidmap: null
uidmap: null
kernel: 6.10.10-200.fc40.aarch64
linkmode: dynamic
logDriver: journald
memFree: 842330112
memTotal: 7716700160
networkBackend: netavark
networkBackendInfo:
backend: netavark
dns:
package: aardvark-dns-1.12.1-1.20240925084542154505.main.19.g56d105f.fc40.aarch64
path: /usr/libexec/podman/aardvark-dns
version: aardvark-dns 1.13.0-dev
package: netavark-1.12.1-1.20240913132227547291.main.38.gcebebc7.fc40.aarch64
path: /usr/libexec/podman/netavark
version: netavark 1.13.0-dev
ociRuntime:
name: crun
package: crun-1.17-1.20240910121144502937.main.3.g4ab4ac0.fc40.aarch64
path: /usr/bin/crun
version: |-
crun version UNKNOWN
commit: fa61d61334521bb205430e928df99f947716f88c
rundir: /run/crun
spec: 1.0.0
+SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +LIBKRUN +WASM:wasmedge +YAJL
os: linux
pasta:
executable: /usr/bin/pasta
package: passt-0^20240906.g6b38f07-1.fc40.aarch64
version: |
pasta 0^20240906.g6b38f07-1.fc40.aarch64-pasta
Copyright Red Hat
GNU General Public License, version 2 or later
<https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
remoteSocket:
exists: true
path: /run/podman/podman.sock
rootlessNetworkCmd: pasta
security:
apparmorEnabled: false
capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
rootless: false
seccompEnabled: true
seccompProfilePath: /usr/share/containers/seccomp.json
selinuxEnabled: true
serviceIsRemote: true
slirp4netns:
executable: /usr/bin/slirp4netns
package: slirp4netns-1.2.2-2.fc40.aarch64
version: |-
slirp4netns version 1.2.2
commit: 0ee2d87523e906518d34a6b423271e4826f71faf
libslirp: 4.7.0
SLIRP_CONFIG_VERSION_MAX: 4
libseccomp: 2.5.5
swapFree: 0
swapTotal: 0
uptime: 771h 50m 58.00s (Approximately 32.12 days)
variant: v8
plugins:
authorization: null
log:
- k8s-file
- none
- passthrough
- journald
network:
- bridge
- macvlan
- ipvlan
volume:
- local
registries:
search:
- docker.io
store:
configFile: /usr/share/containers/storage.conf
containerStore:
number: 7
paused: 0
running: 7
stopped: 0
graphDriverName: overlay
graphOptions:
overlay.imagestore: /usr/lib/containers/storage
overlay.mountopt: nodev,metacopy=on
graphRoot: /var/lib/containers/storage
graphRootAllocated: 99252940800
graphRootUsed: 37016104960
graphStatus:
Backing Filesystem: xfs
Native Overlay Diff: "false"
Supports d_type: "true"
Supports shifting: "true"
Supports volatile: "true"
Using metacopy: "true"
imageCopyTmpDir: /var/tmp
imageStore:
number: 257
runRoot: /run/containers/storage
transientStore: false
volumePath: /var/lib/containers/storage/volumes
version:
APIVersion: 5.2.3
Built: 1727136000
BuiltTime: Tue Sep 24 02:00:00 2024
GitCommit: ""
GoVersion: go1.22.7
Os: linux
OsArch: linux/arm64
Version: 5.2.3
What happened?
I'm adding a file with WithResourceMapping. But inside the container, the file is an empty directory.
private readonly KeycloakContainer container = new KeycloakBuilder()
.WithImage("quay.io/keycloak/keycloak:24.0.5")
.WithUsername(MasterUsername)
.WithPassword(MasterPassword)
.WithResourceMapping(
new FileInfo("TestContainers/temporary.json"),
"/opt/keycloak/data/import/temporary.json"
)
.WithEnvironment("KC_HOSTNAME_STRICT", "false")
.WithEnvironment("KC_HOSTNAME_STRICT_HTTPS", "false")
.WithEnvironment("KC_HOSTNAME_STRICT_BACKCHANNEL", "true")
.WithCommand("--import-realm")
.Build();
bash-5.1$ ls -la /opt/keycloak/data/import/
total 0
drwxr-xr-x. 3 root root 28 Jul 17 08:49 .
drwxrwxr-x. 1 keycloak root 30 Jul 17 08:49 ..
drwxr-xr-x. 2 root root 28 Jul 17 08:49 temporary.json
Relevant log output
Additional information
No response
The second arg should be a directory (docs). Change it to:
.WithResourceMapping(
new FileInfo("TestContainers/temporary.json"),
"/opt/keycloak/data/import/"
)
But inside the container, the file is an empty directory.
Even though the second arg isn't "correct", it shouldn't be empty. Is the path to TestContainers/temporary.json correct?
Even though the second arg isn't "correct", it shouldn't be empty. Is the path to TestContainers/temporary.json correct?
No, you are right. The path isn't empty. It contains the file.
While the issue is resolved for me at this point, I still like to express the following thoughts:
To me, it is unexpected that I can't put a file path as the second parameter, as I'm used to doing this in docker-compose.yml:
services:
iam:
image: quay.io/keycloak/keycloak:24.0.5
environment:
KEYCLOAK_ADMIN: admin
KEYCLOAK_ADMIN_PASSWORD: admin
command:
- start-dev
- --import-realm
- --health-enabled=true
- --hostname-url=http://localhost:8080
- --hostname-strict=false
- --hostname-strict-https=false
- --hostname-strict-backchannel=true
volumes:
- keycloak-db:/opt/keycloak/data/h2
- ./Requirements/TestContainers/temporary.json:/opt/keycloak/data/import/temporary.json
ports:
- '8080:8080'
healthcheck:
test: ["CMD", "bash", "-c", "</dev/tcp/localhost/8080"]
interval: '10s'
timeout: '1s'
retries: 5
start_period: '20s'
I would have appreciated it if the documentation was more explicit about this (that is, expecting only directories).
Also, the API is slightly inconsistent in my opinion, as the overload that accepts a byte array expects a file path. Same method name, various meanings for the second path parameter:
_ = new ContainerBuilder()
.WithResourceMapping(new DirectoryInfo("."), "/DIRECTORY/");
_ = new ContainerBuilder()
.WithResourceMapping(new FileInfo("file.txt"), "/DIRECTORY/");
_ = new ContainerBuilder()
.WithResourceMapping(Encoding.Default.GetBytes("{}"), "/FILE");
Also, the API is slightly inconsistent in my opinion, as the overload that accepts a byte array expects a file path. Same method name, various meanings for the second path parameter:
Yeah, it's definitely not ideal. It's mostly because of some really old APIs, to keep them backward compatible. Also, when working with just a string, there's no reliable way to tell whether the target is a directory or a file (the overloads use a different arg name, but it's not intuitive, I get that 😄). If the target is a file, use the overload WithResourceMapping(FileInfo source, FileInfo target).
I would have appreciated it if the documentation was more explicit about this (that is, expecting only directories).
Would you be interested in contributing to the (XML) docs to help clarify this?
Edit: We can also refactor this as long as we maintain backward compatibility, so developers can smoothly transition to the new API/behavior. Ideally, we'd use the same source and target types (I guess):
https://github.com/testcontainers/testcontainers-dotnet/blob/94abb4a3eeb3d5ecf9ba569c99832fcb5e9f8a95/src/Testcontainers/Builders/ContainerBuilder%603.cs#L210-L227
Would you be interested in contributing to the (XML) docs to help clarify this?
https://github.com/testcontainers/testcontainers-dotnet/pull/1487 (https://deploy-preview-1487--testcontainers-dotnet.netlify.app/api/create_docker_container/)
Also, when working with just a string, there's no reliable way to tell whether the target is a directory or a file
It's possible to tell whether a path is a directory, which is always the case if the path ends with a /. If a path does not end in a /, it's impossible to tell without breaking backward compatibility.
The string-based methods could be deprecated instead and replaced with the following methods. These signatures are explicit with regards to the target path being a file or directory path.
WithResourceMapping(FileInfo, DirectoryInfo, UnixFileModes fileMode = Unix.FileMode644);
WithResourceMapping(FileInfo, FileInfo, UnixFileModes fileMode = Unix.FileMode644);
WithResourceMapping(DirectoryInfo, DirectoryInfo, UnixFileModes fileMode = Unix.FileMode644);
WithResourceMapping(byte[], FileInfo, UnixFileModes fileMode = Unix.FileMode644);
WithResourceMapping(Uri, FileInfo, UnixFileModes fileMode = Unix.FileMode644);
WithResourceMapping(Uri, DirectoryInfo, UnixFileModes fileMode = Unix.FileMode644);
The string-based methods could be deprecated instead and replaced with the following methods.
I like this suggestion 👍.
It's possible to tell whether a path is a directory, which is always the case if the path ends with a
/.
Exactly. Should we refactor WithResourceMapping(string, string) and accept the breaking change for a better user experience? WDYT?
Would you be interested in contributing to these changes?
Would you be interested in contributing to these changes?
Please see my proposal in PR https://github.com/testcontainers/testcontainers-dotnet/pull/1497.