Shellhttpd Recipe

All applications installed on your platform are described by a recipe.

A recipe is a file with the application name, version and extension .bb. To create the application shellhttpd the corresponding recipe will have the name: shellhttpd_0.1.bb.

In the meta-subscriber-overrides folder, create the recipes-support folder.

mkdir recipes-support

In the recipes-support folder, use git to download the shellhttpd recipe from the extra-meta-subscriber-overrides repository:

cd recipes-support
git remote add fio https://github.com/foundriesio/extra-meta-subscriber-overrides.git
git remote update
git checkout remotes/fio/main -- shellhttpd

The shellhttpd recipe should be inside the recipes-support folder:

tree -L 3 .

Example output:

└── shellhttpd
    ├── shellhttpd
    │   ├── httpd.sh
    │   └── shellhttpd.service
    └── shellhttpd_0.1.bb

Check the content of your shellhttpd/shellhttpd_0.1.bb file:

cat shellhttpd/shellhttpd_0.1.bb

shellhttpd/shellhttpd_0.1.bb:

SUMMARY = "Start up Shellhttpd Application"
LICENSE = "MIT"
LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"

inherit allarch systemd
RDEPENDS:${PN} += "bash"

SRC_URI = " \
        file://httpd.sh \
        file://shellhttpd.service \
"
SRCREV = "f90f221ce4fcea2fde0062bc909f26cca6dbd1b6"

S = "${WORKDIR}/git"

PACKAGE_ARCH = "${MACHINE_ARCH}"

SYSTEMD_SERVICE:${PN} = "shellhttpd.service"
SYSTEMD_AUTO_ENABLE:${PN} = "enable"

do_install () {
        install -d ${D}${systemd_system_unitdir}
        install -m 0644 ${WORKDIR}/shellhttpd.service ${D}${systemd_system_unitdir}
        install -d ${D}${datadir}/shellhttpd/
        install -m 0755 ${WORKDIR}/httpd.sh ${D}${datadir}/shellhttpd/
}

FILES:${PN} += "${systemd_system_unitdir}/shellhttpd.service"
FILES:${PN} += "${systemd_unitdir}/system-preset"
FILES:${PN} += "${datadir} ${datadir}/app-manager/"

The shellhttpd/shellhttpd_0.1.bb file has all the details for the shellhttpd application.

This tutorial does not intend to cover the Yocto Project concepts. However, let’s highlight the following variables:

• SRC_URI: It is including the files httpd.sh and shellhttpd.service in the ${WORKDIR}.
• do_install: It is installing the file from ${WORKDIR} to the Linux distribution root file system.

Check the content of your shellhttpd/shellhttpd/httpd.sh file:

cat shellhttpd/shellhttpd/httpd.sh

shellhttpd/shellhttpd/httpd.sh:

#!/bin/sh -e

PORT="${PORT-8090}"
MSG="${MSG-OK}"

RESPONSE="HTTP/1.1 200 OK\r\n\r\n${MSG}\r\n"

while true; do
   echo -en "$RESPONSE" | nc -c -l -p "${PORT}" || true
   echo "= $(date) ============================="
done

The shellhttpd/shellhttpd/httpd.sh is very similar to the httpd.sh used in the previous tutorials.

This is the shell script executed by the shellhttpd.service file.

Check the content of your shellhttpd/shellhttpd/shellhttpd.service file:

cat shellhttpd/shellhttpd/shellhttpd.service

shellhttpd/shellhttpd/shellhttpd.service:

[Unit]
Description=Shellhttpd Minimal Web Server
DefaultDependencies=no
After=systemd-udev-settle.service
Before=sysinit.target shutdown.target
Conflicts=shutdown.target
Description=Start up Shellhttpd Application

[Service]
ExecStart=/bin/sh /usr/share/shellhttpd/httpd.sh
RemainAfterExit=true

[Install]
WantedBy=sysinit.target

The shellhttpd/shellhttpd/shellhttpd.service is a systemd service. The only variable that should be highlight here is:

• ExecStart: Execute the httpd.sh script.