smalltalk programming for the web

Iceberg and SSH keys

5 August 2017

On a laptop that I've just rebuilt recently, I created and have been using an ED25519 SSH key pair, including with Github. Iceberg doesn't work with it though, throwing the error 'LGit_GIT_ERROR: No ssh-agent suitable credentials found". This is because Iceberg uses libgit2, which uses libssh2, which apparently doesn't support ED25519 keys. Created a new RSA key pair, registered it with Github, and Iceberg works.

  • OS = Linux Mint 18.1
  • Pharo image = 60510-64
  • Pharo VM = pulled from GH opensmalltalk-vm today and built on said laptop

Proof of Concept: FileTree and Fossil

28 February 2017

While putting up PasswordCrypt on Github, I was working with its local FileTree repository. I found the workflow cumbersome - committing in Pharo causes untracked files and so on as seen by Git, which had to be resolved by hand, followed by 'git commit' and 'git push'. I know that tools like GitFileTree and Iceberg are meant to smoothen the workflow. I also know that I don't know Git well at all.

OTOH, I use multiple computers - a main Linux/Windows workstation, a Mac, and a small laptop for tinkering on the go - and keeping all my mcz files in sync on these computers is getting to be a chore.

I am a fan of Fossil. In addition to being a DVCS a la Git, Fossil comes with a wiki, ticketing system, simple HTTP-based networking to sync repositories, and other good stuff. This blog's content is managed using Fossil.

However, using Fossil in place of Git to manage FileTree repositories at the directories/files level still requires the 2-step workflow: commit in Pharo, fix up the changes with Fossil, commit in Fossil.

So I wrote a simple integration of FileTree with Fossil.

At the operating system command prompt, init a new Fossil project:

os% mkdir ~/repo
os% cd ~/repo
os% fossil init myproject.fossil
project-id: 3c05c3016eeabf8e87816ee218c6a86d3c87b950
server-id:  ff42bc86dba1a26b1d94b64685f7c09d02581617
admin-user: laptop-user (initial password is "1fe2ff")

Open the repository:

os% mkdir ~/myproject
os% cd ~/myproject
os% fossil open ~/repo/myproject.fossil

In a fresh Pharo 6 image - I used v60411 - install FossilFileTree:

Metacello new 
  baseline: 'FossilFileTree'; 
  repository: 'github://PierceNg/FossilFileTree'; 

Write code in Pharo. Open Monticello Browser. Add a "fossilfiletree" repository, using ~/myproject as the directory. Save to said repository from within Monticello Browser. Done.

To check what Fossil got, run 'fossil status' in ~/myproject. The last line 'comment: ...' contains the in-Pharo commit message.

And now I get to use Fossil to keep my FileTree repositories in sync among my computers.


  • I basically copied GitFileTree's use of OSSubprocess to call the Fossil executable.
  • Tested on Linux with recent Pharo 6 only. I tried to install on a Pharo 5 image, but the installation hung somewhere.
  • The above is all this thing does. For all other Fossil-related operations - clone, sync/push/pull - use Fossil.
  • Not written any test.

Logging libraries for Pharo 5

19 February 2017

Below are the logging libraries that I've found for Pharo/Squeak:

  • Log4s
  • Nagare
  • OsmoSyslog
  • Syslog
  • SystemLogger
  • Toothpick

Log4s for Pharo is a port of the VA Smalltalk port of the popular Java logging framework Log4j. I installed it from Pharo 5's catalog browser. 206 of 207 tests passed, with 1 failure. None of the classes is commented, although being a port of Log4j, the Java documentation should work as reference.

Nagare is a "flexible logger which connects to Fluentd." It was written to run on VisualWorks, Squeak and Pharo. I installed it from the catalog browser. None of the classes is commented. No test suite. Documentation remains on the Google Code project wiki.

OsmoSyslog is a "log backend/target to use system syslog." AGPLv3+. I stopped there.

Syslog is an RFC5452 Syslog UDP client. I installed it using a Gofer snippet. It loads OSProcess. Every class has a class comment. Test suite has four tests. Because I have OSSubprocess in the same image I did not attempt to run the tests.

SystemLogger "is an easy to use, very lightweight, and highly configurable object logging framework." It failed to install from the catalog browser but loaded successfully using a Gofer snippet. Every class has a class comment. 17 of 19 tests passed, with 2 failures.

Toothpick is a port to Pharo of the Smalltalk library written to run on Dolphin, Squeak, VisualAge and VisualWorks. Documentation on the original site looks good. 16 of 19 tests passed, with 1 failure and 2 errors.

Automating web content deployment with Fossil

12 August 2016

I've migrated this site to Pharo 5 from Pharo 3. One notable behind-the-scene change is that content is now deployed using Fossil, the "simple, high-reliability, distributed software configuration management system". Fossil is usually compared with DVCS such as Git and Mercurial.

This server runs the published version of this site. (Of course.) The development version is on my laptop. Now, when I wish to publish changes from my development version, say, when I have written a new blog post, I 'fossil commit', then 'fossil push', whereupon the new blog post and associated artefacts such as images are deployed into the published version on this server.

There are any number of articles on the web describing using Git hooks to automate deploying web content. In this post, I describe using Fossil to do the same. Some familiarity with Fossil is assumed.


To begin, build Fossil with TH1 hooks and Tcl integration. Deploy it both locally and on the server, by copying the single Fossil executable to appropriate directories.

Create a new repostory locally. Take note of the admin user ID and generated password. Let's assume that the admin user ID is 'laptop-user'. Be aware that Fossil has its own user IDs, passwords and roles, distinct from the underlying operating system's.

laptop% mkdir ~/repo
laptop% cd ~/repo
laptop% fossil init webtree.fossil
project-id: 3c05c3016eeabf8e87816ee218c6a86d3c87b950
server-id:  ff42bc86dba1a26b1d94b64685f7c09d02581617
admin-user: laptop-user (initial password is "1fe2ff")

Check out the repository locally:

laptop% mkdir ~/webtree
laptop% cd ~/webtree
laptop% fossil open ~/repo/webtree.fossil

Add new content:

laptop% cd ~/webtree
laptop% echo "Hello, world, from Fossil." > helloworld.txt
laptop% fossil add helloworld.txt 
laptop% fossil commit -m "First commit." 

Upon commit, the repository, ~/repo/webtree.fossil, is updated. Note that the repository is a single file that can be copied, renamed, moved to other computers, etc. Let's scp it to our server and set up the following directory structure there. Here I use /x to keep path names short for this post.

    fossil         <= The Fossil executable.
    fossilupdate   <= Shell script, described below.
  webtree/         <= Checked out tree of webtree.fossil.
    webtree.fossil <= The repository.

To populate /x/webtree:

server% cd /x/webtree
server% fossil open /x/repo/webtree.fossil
server% ls -a
./  ../  .fslckout  helloworld.txt

The file .fslckout is Fossil's checkout database.

Create the shell script /x/bin/fossilupdate:

server% cd /x/bin
server% cat > fossilupdate
cd /x/webtree
/x/bin/fossil update
server% chmod 755 fossilupdate

Run the Fossil server. Here I use port 8081.

server% cd /x/webtree
server% /x/bin/fossil server --port 8081
Listening for HTTP requests on TCP port 8081

With your web browser, navigate to the Fossil server and login using the admin user ID and password you noted down earlier. Go to Admin > Settings. Disable autosync, enable tcl, enable th1-hooks, and click 'Apply Changes'. Go to Admin > Transfers > Push. Enter below command into the text box and click 'Apply Changes'.

tclInvoke exec /x/bin/fossilupdate & 

This sets up the Fossil transfer hook, which will fire after your Fossil server processes a 'fossil push' request.

Back on the laptop, commit another file:

laptop% cd ~/webtree
laptop% echo "Hello again." > take2.txt
laptop% fossil add take2.txt
laptop% fossil commit -m "Take 2."
laptop% fossil push http://laptop-user@server:8081/
password for laptop-user: 
remember password (Y/n)? n
Round-trips: 2   Artifacts sent: 2  received: 0
Push done, send: 1075  received: 1199  ip: <server>

The push from the laptop will trigger the abovementioned transfer hook configured in the server's Fossil server instance, which will update /x/webtree on the server. Viola!

Automatically starting the Fossil server

It is often desirable to start the Fossil server automatically upon server startup. On my server, I use daemontools. However, for some reason daemontools' setuidgid program is unable to run 'fossil server' in the correct directory. So I use Ubuntu's start-stop-daemon instead, and this is the daemontools run file:

exec /sbin/start-stop-daemon --start \
  -c cms:cms -d /x/webtree \
  --exec /x/bin/fossil \
  -- server --port 8081

Create a new user, say, 'cms', and set up ownership of /x:

User:Group   Dir/File
root:root    /x/
root:root      bin/
root:root        fossil
root:root        fossilupdate
cms:cms        webtree/
cms:cms        repo/
cms:cms          webtree.fossil
root:root        run <= daemontools run file

Link /x/repo into daemontools, and 'fossil server' runs as the 'cms' user in /x/webtree.


/x/webtree/.fslckout is Fossil's checkout database. If your web server serves content directly from /x/webtree, you should configure it to not serve the .fslckout file.

An alternate practice (according to those Git hook articles) is to rsync the content of /x/webtree to another directory, and it is this second directory that the web server reads from. In such a case, it is still necessary to avoid rsync'ing the .fslckout file.

Users in Fossil

As mentioned, Fossil maintains its own user IDs, passwords, and roles. In this post, I assumed that the Fossil admin user is called 'laptop-user' and used it for 'fossil push'. It is preferable to set up a separate lower privileged Fossil user and use that instead.