# balenaCloud emulated build breaks application **URL:** \ **Category:** Product support\ **Tags:** builder\ **Created:** [September 30, 2020, 9:23am UTC](https://forums.balena.io/t/balenacloud-emulated-build-breaks-application/194951 "2020-09-30T09:23:46Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![pdboef](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/pdboef/32/4342_2.png) [@pdboef](https://forums.balena.io/u/pdboef)\ **Post date:** [September 30, 2020, 9:23am UTC](https://forums.balena.io/t/balenacloud-emulated-build-breaks-application/194951/1 "2020-09-30T09:23:46Z")
Yesterday, my [Telegraf](https://github.com/influxdata/telegraf) service suddenly crashed after pushing a new build. After further inspection, I found out that the issue was caused by an emulated build. I’ve set up a small [repository](https://github.com/pascal-hwky/balenacloud-emulation) to reliably reproduce the issue. For convenience, I’ve posted the README of this repo below. ## Problem statement balenaCloud offers two types of builders for ARM devices: 1. Native ARM builders 2. [x86 builders using QEMU emulation](https://www.balena.io/docs/learn/deploy/deployment/#--emulated--e) This repository shows that there are applications for which these two builders do not produce the same output. In fact, emulated building _produces a broken container_. The sample application provided is extremely simple and consists of a single `Dockerfile` containing the following line: ```auto FROM telegraf ``` ## Prerequisites 1. A [balenaCloud](https://dashboard.balena-cloud.com/) account. 2. Installation of [balena-cli](https://github.com/balena-io/balena-cli). 3. A balenaCloud application named `balenacloud-emulation` with an ARM device type (such as a Raspberry Pi) and at least one device. ## Steps to reproduce Run the following commands to download this repository and reproduce the issue: ```auto git clone https://github.com/pascal-hwky/balenacloud-emulation.git cd balenacloud-emulation balena push balenacloud-emulation --emulated ``` After the deployment is completed, you should see the following device output: ```auto standard_init_linux.go:211: exec user process caused "exec format error" ``` This error message indicates that the Docker image contains invalid instructions and was therefore compiled for a different architecture. Repeating the build _without emulation_ (by leaving out the `--emulated` flag) does not cause this issue. The balena-cli [documentation](https://www.balena.io/docs/learn/deploy/deployment/#--emulated--e) mentions the following: > The emulated builds will also happen on the rare occasion that the native ARM builder is overloaded or unavailable. However, as in the above case the emulated build fails, this could cause applications to randomly crash. ---
**Author:** ![pdcastro](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/pdcastro/32/1264_2.png) [@pdcastro](https://forums.balena.io/u/pdcastro)\ **Post date:** [September 30, 2020, 7:33pm UTC](https://forums.balena.io/t/balenacloud-emulated-build-breaks-application/194951/9 "2020-09-30T19:33:03Z")
@pdboef, thank you for reporting this issue and preparing the repo for reproduction. The issue is probably that `telegraf` is a “multi-architecture” Dockerhub image (where a single image name:tag refers to multiple different images of different architectures, such as as ARM and Intel x86), which is not yet fully supported by the balenaCloud builders or the balena CLI. We are working towards adding multiarch image support. Meanwhile, the workaround you may use is to append a sha256 digest to the FROM line of your Dockerfile, thus “manually selecting” the base image architecture. To do so, check the different sha256 digest for each available architecture on the Dockerhub page: - [https://hub.docker.com/layers/telegraf/library/telegraf/1.15.3/images/sha256-c29f6cd7a329f91e631a1c24c5210d05c81541d2d4bbf39b1298a7e2866bfd1e?context=explore](https://hub.docker.com/layers/telegraf/library/telegraf/1.15.3/images/sha256-c29f6cd7a329f91e631a1c24c5210d05c81541d2d4bbf39b1298a7e2866bfd1e?context=explore) | Dockerhub arch | Device | Dockerfile FROM line | | --- | --- | --- | | arm64/v8 | RPi 4 | FROM telegraf:1.15.3@sha256:fd61aa216d0bd94fb868075c3ead2a933949d738a74a0e8c6720729a8b722e9d | | arm/v7 | RPi 3 | FROM telegraf:1.15.3@sha256:ff07f829cae2b0c5305b09d534ab2ddb868900aaf06e32f93722919a155e0e21 | | amd64 | Intel NUC | FROM telegraf:1.15.3@sha256:c29f6cd7a329f91e631a1c24c5210d05c81541d2d4bbf39b1298a7e2866bfd1e | Choose one of the Dockerfile FROM lines from the table above, depending on your device type. The sha256 digests above were extracted from the Dockerhub page linked above, by using the dropdown box to select the target architecture. Let us know if this workaround works for you. To track our progress on adding multiarch image support, you can subscribe to this GitHub issue: [https://github.com/balena-io/balena-cli/issues/1508](https://github.com/balena-io/balena-cli/issues/1508) I am also linking that GitHub issue and other internal resources to this forum thread, so that we can also notify you on this thread when the work on multiarch image support is done. ---
**Author:** ![pdboef](https://sea2.discourse-cdn.com/balena/user_avatar/forums.balena.io/pdboef/32/4342_2.png) [@pdboef](https://forums.balena.io/u/pdboef)\ **Post date:** [September 30, 2020, 9:10pm UTC](https://forums.balena.io/t/balenacloud-emulated-build-breaks-application/194951/12 "2020-09-30T21:10:38Z")
Hi @pdcastro, thanks for the quick response. This workaround is perfectly acceptable for us 🙂