Confirm validity of downloaded FTL binary when building

[PromoFaux]

What does this PR aim to accomplish?:

Addresses comment by @DL6ER here pi-hole/FTL#2035 (comment)

The Dockerfile had a readelf command to check the downloaded binary was a binary, but really we should be hard existing if it is invalid.

Adds some additional output to the build.sh to inform the user that something went wrong, or indeed that everything is OK.

Successful build

adam@adam-pc:~/repos/docker-pi-hole$ ./build.sh
Executing command: docker buildx build src/. --tag pihole:local --load --no-cache
[+] Building 5.3s (19/19) FINISHED                                                                                                                                                 docker:default
 => [internal] load build definition from Dockerfile                                                                                                                                         0.0s
 => => transferring dockerfile: 4.09kB                                                                                                                                                       0.0s
 => resolve image config for docker-image://docker.io/docker/dockerfile:1                                                                                                                    0.6s
 => CACHED docker-image://docker.io/docker/dockerfile:1@sha256:865e5dd094beca432e8c0a1d5e1c465db5f998dca4e439981029b3b81fb39ed5                                                              0.0s
 => [internal] load metadata for docker.io/library/alpine:3.20                                                                                                                               0.5s
 => [internal] load .dockerignore                                                                                                                                                            0.0s
 => => transferring context: 82B                                                                                                                                                             0.0s
 => CACHED [base 1/9] FROM docker.io/library/alpine:3.20@sha256:beefdbd8a1da6d2915566fde36db9db0b524eb737fc57cd1367effd16dc0d06d                                                             0.0s
 => CACHED [base 3/9] ADD https://ftl.pi-hole.net/macvendor.db /macvendor.db                                                                                                                 0.0s
 => [internal] load build context                                                                                                                                                            0.0s
 => => transferring context: 98B                                                                                                                                                             0.0s
 => CACHED [base 5/9] ADD --chmod=0755 https://raw.githubusercontent.com/pi-hole/PADD/development/padd.sh /usr/local/bin/padd                                                                0.0s
 => [base 2/9] RUN apk add --no-cache     bash     bind-tools     binutils     coreutils     curl     git     grep     iproute2-ss     jq     libcap     logrotate     ncurses     nmap-nca  1.2s
 => [base 3/9] ADD https://ftl.pi-hole.net/macvendor.db /macvendor.db                                                                                                                        0.0s
 => [base 4/9] COPY crontab.txt /crontab.txt                                                                                                                                                 0.0s
 => [base 5/9] ADD --chmod=0755 https://raw.githubusercontent.com/pi-hole/PADD/development/padd.sh /usr/local/bin/padd                                                                       0.0s
 => [base 6/9] RUN git clone --depth 1 --single-branch --branch development https://github.com/pi-hole/web.git /var/www/html/admin &&     git clone --depth 1 --single-branch --branch deve  1.3s
 => [base 7/9] RUN cd /etc/.pihole &&     install -Dm755 -d /opt/pihole &&     install -Dm755 -t /opt/pihole gravity.sh &&     install -Dm755 -t /opt/pihole ./advanced/Scripts/*.sh &&      0.4s 
 => [base 8/9] COPY --chmod=0755 bash_functions.sh /usr/bin/bash_functions.sh                                                                                                                0.0s 
 => [base 9/9] COPY --chmod=0755 start.sh /usr/bin/start.sh                                                                                                                                  0.0s
 => [remote-ftl-install 1/1] RUN if   [ "linux/amd64" = "linux/amd64" ];    then FTLARCH=amd64;     elif [ "linux/amd64" = "linux/386" ];      then FTLARCH=386;     elif [ "linux/amd64" =  0.9s
 => exporting to image                                                                                                                                                                       0.2s
 => => exporting layers                                                                                                                                                                      0.2s
 => => writing image sha256:9c94987e2ed941acf41e9d14cc7c8b540861ca8ef17c71de5afb695c145c18f8                                                                                                 0.0s 
 => => naming to docker.io/library/pihole:local                                                                                                                                              0.0s 
                                                                                                                                                                                                  
Successfully built Docker image with tag 'pihole:local'                                                                                                                                           
REPOSITORY   TAG       IMAGE ID       CREATED                  SIZE
pihole       local     9c94987e2ed9   Less than a second ago   89.9MB

Unsuccessful build

adam@adam-pc:~/repos/docker-pi-hole$ ./build.sh -f non-existant-ftl-branch
Executing command: docker buildx build src/. --tag pihole:local --load --no-cache --build-arg FTL_BRANCH=non-existant-ftl-branch
[+] Building 4.4s (18/18) FINISHED                                                                                                                                                 docker:default
 => [internal] load build definition from Dockerfile                                                                                                                                         0.0s
 => => transferring dockerfile: 4.09kB                                                                                                                                                       0.0s
 => resolve image config for docker-image://docker.io/docker/dockerfile:1                                                                                                                    0.4s
 => CACHED docker-image://docker.io/docker/dockerfile:1@sha256:865e5dd094beca432e8c0a1d5e1c465db5f998dca4e439981029b3b81fb39ed5                                                              0.0s
 => [internal] load metadata for docker.io/library/alpine:3.20                                                                                                                               0.3s
 => [internal] load .dockerignore                                                                                                                                                            0.0s
 => => transferring context: 82B                                                                                                                                                             0.0s
 => CACHED [base 1/9] FROM docker.io/library/alpine:3.20@sha256:beefdbd8a1da6d2915566fde36db9db0b524eb737fc57cd1367effd16dc0d06d                                                             0.0s
 => CACHED [base 3/9] ADD https://ftl.pi-hole.net/macvendor.db /macvendor.db                                                                                                                 0.0s
 => [internal] load build context                                                                                                                                                            0.0s
 => => transferring context: 98B                                                                                                                                                             0.0s
 => CACHED [base 5/9] ADD --chmod=0755 https://raw.githubusercontent.com/pi-hole/PADD/development/padd.sh /usr/local/bin/padd                                                                0.0s
 => [base 2/9] RUN apk add --no-cache     bash     bind-tools     binutils     coreutils     curl     git     grep     iproute2-ss     jq     libcap     logrotate     ncurses     nmap-nca  1.2s
 => [base 3/9] ADD https://ftl.pi-hole.net/macvendor.db /macvendor.db                                                                                                                        0.0s 
 => [base 4/9] COPY crontab.txt /crontab.txt                                                                                                                                                 0.0s 
 => [base 5/9] ADD --chmod=0755 https://raw.githubusercontent.com/pi-hole/PADD/development/padd.sh /usr/local/bin/padd                                                                       0.0s 
 => [base 6/9] RUN git clone --depth 1 --single-branch --branch development https://github.com/pi-hole/web.git /var/www/html/admin &&     git clone --depth 1 --single-branch --branch deve  1.3s 
 => [base 7/9] RUN cd /etc/.pihole &&     install -Dm755 -d /opt/pihole &&     install -Dm755 -t /opt/pihole gravity.sh &&     install -Dm755 -t /opt/pihole ./advanced/Scripts/*.sh &&      0.4s 
 => [base 8/9] COPY --chmod=0755 bash_functions.sh /usr/bin/bash_functions.sh                                                                                                                0.0s 
 => [base 9/9] COPY --chmod=0755 start.sh /usr/bin/start.sh                                                                                                                                  0.0s
 => ERROR [remote-ftl-install 1/1] RUN if   [ "linux/amd64" = "linux/amd64" ];    then FTLARCH=amd64;     elif [ "linux/amd64" = "linux/386" ];      then FTLARCH=386;     elif [ "linux/am  0.6s
------                                                                                                                                                                                            
 > [remote-ftl-install 1/1] RUN if   [ "linux/amd64" = "linux/amd64" ];    then FTLARCH=amd64;     elif [ "linux/amd64" = "linux/386" ];      then FTLARCH=386;     elif [ "linux/amd64" = "linux/arm/v6" ];   then FTLARCH=armv6;     elif [ "linux/amd64" = "linux/arm/v7" ];   then FTLARCH=armv7;     elif [ "linux/amd64" = "linux/arm64" ];    then FTLARCH=arm64;     elif [ "linux/amd64" = "linux/riscv64" ];  then FTLARCH=riscv64;     else FTLARCH=amd64; fi     && echo "Arch: linux/amd64, FTLARCH: ${FTLARCH}"     && curl -sSL "https://ftl.pi-hole.net/non-existant-ftl-branch/pihole-FTL-${FTLARCH}" -o /usr/bin/pihole-FTL     && chmod +x /usr/bin/pihole-FTL     && readelf -h /usr/bin/pihole-FTL || (cat /usr/bin/pihole-FTL && echo "Error with downloaded FTL binary" && exit 1):
0.525 Arch: linux/amd64, FTLARCH: amd64
0.544 readelf: Error: Not an ELF file - it has the wrong magic bytes at the start
0.545 <html>
0.545 <head><title>404 Not Found</title></head>
0.545 <body>
0.545 <center><h1>404 Not Found</h1></center>
0.545 <hr><center>nginx/1.25.0</center>
0.545 </body>
0.545 </html>
0.545 Error with downloaded FTL binary
------
Dockerfile:75
--------------------
  74 |     # Download the latest version of pihole-FTL for the correct architecture
  75 | >>> RUN if   [ "$TARGETPLATFORM" = "linux/amd64" ];    then FTLARCH=amd64; \
  76 | >>>     elif [ "$TARGETPLATFORM" = "linux/386" ];      then FTLARCH=386; \
  77 | >>>     elif [ "$TARGETPLATFORM" = "linux/arm/v6" ];   then FTLARCH=armv6; \
  78 | >>>     elif [ "$TARGETPLATFORM" = "linux/arm/v7" ];   then FTLARCH=armv7; \
  79 | >>>     # Note for the future, "linux/arm6/v8" is not a valid value for TARGETPLATFORM, despite the CI platform name being that.
  80 | >>>     elif [ "$TARGETPLATFORM" = "linux/arm64" ];    then FTLARCH=arm64; \
  81 | >>>     elif [ "$TARGETPLATFORM" = "linux/riscv64" ];  then FTLARCH=riscv64; \
  82 | >>>     else FTLARCH=amd64; fi \
  83 | >>>     && echo "Arch: ${TARGETPLATFORM}, FTLARCH: ${FTLARCH}" \
  84 | >>>     && curl -sSL "https://ftl.pi-hole.net/${FTL_BRANCH}/pihole-FTL-${FTLARCH}" -o /usr/bin/pihole-FTL \
  85 | >>>     && chmod +x /usr/bin/pihole-FTL \
  86 | >>>     && readelf -h /usr/bin/pihole-FTL || (cat /usr/bin/pihole-FTL && echo "Error with downloaded FTL binary" && exit 1)
  87 |     
--------------------
ERROR: failed to solve: process "/bin/sh -c if   [ \"$TARGETPLATFORM\" = \"linux/amd64\" ];    then FTLARCH=amd64;     elif [ \"$TARGETPLATFORM\" = \"linux/386\" ];      then FTLARCH=386;     elif [ \"$TARGETPLATFORM\" = \"linux/arm/v6\" ];   then FTLARCH=armv6;     elif [ \"$TARGETPLATFORM\" = \"linux/arm/v7\" ];   then FTLARCH=armv7;     elif [ \"$TARGETPLATFORM\" = \"linux/arm64\" ];    then FTLARCH=arm64;     elif [ \"$TARGETPLATFORM\" = \"linux/riscv64\" ];  then FTLARCH=riscv64;     else FTLARCH=amd64; fi     && echo \"Arch: ${TARGETPLATFORM}, FTLARCH: ${FTLARCH}\"     && curl -sSL \"https://ftl.pi-hole.net/${FTL_BRANCH}/pihole-FTL-${FTLARCH}\" -o /usr/bin/pihole-FTL     && chmod +x /usr/bin/pihole-FTL     && readelf -h /usr/bin/pihole-FTL || (cat /usr/bin/pihole-FTL && echo \"Error with downloaded FTL binary\" && exit 1)" did not complete successfully: exit code: 1

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!! ERROR: Docker build failed, please review logs above !!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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[yubiuser]

Why did you change the TAG stuff?

[PromoFaux]

Why did you change the TAG stuff?

For this part https://github.com/pi-hole/docker-pi-hole/pull/1643/files#diff-4d2a8eefdf2a9783512a35da4dc7676a66404b6f3826a8af9aad038722da6823R101-R105